Interlocking EMI shield

ABSTRACT

An electromagnetic interference shield system is provided. Each EMI shield may include a frame providing the structure around the electronic device components to be shielded, and a cover operative to be placed over the frame to prevent electromagnetic radiation from passing over the frame. Each frame may be coupled to a circuit board, and enclose electronic components in need of shielding. Each cover may be coupled to its corresponding frame using at least one snap that extends from the periphery of the cover towards the frame and circuit board. To minimize the space taken by the EMI shields, the snaps of adjacent covers may be offset or staggered so that opposing snaps engage voids left between snaps of the opposing cover, thus reducing the space needed between adjacent EMI shields by up to the width of a snap.

BACKGROUND OF THE INVENTION

This invention is directed to an interlocking electromagneticinterference (EMI) shield system for use in an electronic device.

Many electronic devices include various electronic components that emitelectromagnetic radiation. To prevent disturbances of the electroniccomponents, EMI shields may be provided in the electronic device. Forexample, the electronic device components may be placed in a conductivebox (e.g., a metallic box) that prevents radiation from escaping thebox. As another example, the enclosure in which the electroniccomponents are placed may be coated with a metallic or conductive paint.

Although these solutions for reducing electromagnetic interferences maybe effective, they may take up significant space, especially in view ofthe size of particular electronic components. For example, a lot ofspace is used to surround a small electrical circuit on all sides with ametallic box. When several electronic components of an electronic deviceneed to be individually shielded, even more space is used to surroundeach component with individual conductive boxes. There is a need,therefore, for an EMI shielding system that takes up little space whileproviding sufficient and effective EMI shielding.

SUMMARY OF THE INVENTION

An interlocking EMI shield system for protecting components of anelectronic device from electromagnetic interferences is provided.

An interlocking EMI shield is provided. Each EMI shield may beconstructed from a frame that is coupled to a circuit board or otherelectronic device structural component, and a cover that is placed overthe frame. The frame may be coupled to the circuit board using anysuitable approach, including for example soldering, a mechanicalfastener, an adhesive, or a snapping mechanism. The frame may includewalls extending around the periphery the shield, and a lip extendingfrom the top edge of the walls towards the center of the shield (e.g.,to provide additional structural support). The walls may include one ormore snaps, tabs, apertures or indentations for receiving acorresponding element from the cover.

Each cover may include a substantially flat surface operative to beplaced over the frame. To couple the cover to the frame, the cover mayinclude several snaps extending vertically from the cover surfacetowards the circuit board to which the frame is coupled. The snaps maybe biased towards the walls of the frame such that the snaps areoperative to engage the walls upon coupling of the cover to the frame.In some embodiments, the snaps may include one or more tabs, prongs, orother elements to engage a counterpoint in the wall of the frame.

Each cover may include any suitable number of snaps. For example, eachcover may include several snaps, each separated by a particular distance(e.g., at least by the width of a snap). The snaps may have the same ordifferent sizes, and be distributed evenly or unevenly along theperiphery of the cover. To reduce the space taken by the shields, thesnaps of shields placed adjacent in the electronic device (e.g., havingedges placed almost in contact) may be offset or staggered such that asnap of a first EMI shield may extend into an indentation of the secondEMI shield (e.g., in between two snaps extending from the second EMIshield), while a snap of the second EMI shield may extend into anindentation of the first EMI shield (e.g., in between two snapsextending from the first EMI shield). Using this staggered approach,space of at least the thickness of one snap may be saved for othercomponents of the electronic device, or to further reduce the size ofthe electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention, its nature andvarious advantages will be more apparent upon consideration of thefollowing detailed description, taken in conjunction with theaccompanying drawings in which:

FIG. 1 is an exploded perspective view of an illustrative EMI shield inaccordance with one embodiment of the invention;

FIG. 2 is a top perspective view of an exploded EMI shield assembly inaccordance with one embodiment of the invention;

FIG. 3 is a perspective view of an EMI shield assembly coupled to acircuit board in accordance with one embodiment of the invention;

FIG. 4 is a perspective view of a detail of the EMI shield assembly ofFIG. 3 along the boundary between the EMI shields in accordance with oneembodiment of the invention;

FIG. 5 is a top view of a detail of the EMI shield assembly of FIG. 3along the boundary between the EMI shields in accordance with oneembodiment of the invention;

FIGS. 6A-6D are top views of a detail of an EMI shield assembly alongthe boundary between EMI shields in accordance with one embodiment ofthe invention; and

FIG. 7 is a top view of a detail of an EMI shield assembly along theboundary between EMI shields in accordance with one embodiment of theinvention.

DETAILED DESCRIPTION

FIG. 1 is an exploded perspective view of an illustrative EMI shieldassembly in accordance with one embodiment of the invention. EMI shieldassembly 100 may be formed from first EMI shield 108 that includes frame110 and cover 120, and second EMI shield 138 that includes frame 140 andcover 150. Each of frames 110 and 140 may include side walls 112 and142, and upper lip or returns 114 and 144, respectively. Side walls 112and 142 may be operative to be coupled to circuit board 130 of anelectronic device to form the side walls of box, for example surroundingelectronic components. Side walls 112 and 142 may be coupled to circuitboard 130 using any suitable approach. For example, side walls 112 and142 may be soldered into circuit board 130, snapped or clipped into astructural element of circuit board 130 (e.g., snaps extending inapertures in the circuit board, or snaps coupling to a receiving elementincorporated in the circuit board), coupled using an adhesive or tape,or using any other suitable approach. In some embodiments, frames 110and 140 may be combined into a single frame having a separating wall(e.g., along boundary 115) onto which distinct covers 120 and 150 may beattached.

Frames 110 and 140 may be placed on any suitable portion of circuitboard 130. For example, frames 110 and 140 may be placed to surroundspecific electronic device components 132 incorporated in circuit board130. In particular, frames 110 and 140 may be placed around differentcomponents 132 that emit electromagnetic radiation, or that aresusceptible to electromagnetic radiation. If circuit board 130 includestwo different components 132, both emitting electromagnetic radiation,and both susceptible to each other's emissions, each may be surroundedby one of frames 110 and 140 to prevent or reduce electromagneticinterferences to the operation of components 132. In addition, using twoseparate EMI shields 108 and 138 with separate covers 120 and 150 thatcan be individually removed may allow for access to particularcomponents 132 (e.g., for repair) without disturbing other componentsthat may be sensitive to interferences from the exposed components.

To prevent radiation from escaping over the end of side wall 112 and142, respectively, covers 120 and 150 may be placed over frames 110 and140, respectively. Once the covers are placed over the frames,components 132 are enclosed in all directions by the cover, side wallsand circuit board, thus preventing interfering radiation from escapingand damaging other components 132. Covers 120 and 150 may include asubstantially flat surface 122 and 152 operative to be placed over eachof frames 110 and 140. Covers 120 and 150 may have any suitableboundaries, including for example boundaries that substantially followside walls 112 and 142, respectively. By providing covers that do notextend past, or minimally extend past side walls 110 and 140, the spacerequired in the electronic device for covers 120 and 150 may beminimized.

Covers 120 and 150 may be coupled to frames 110 and 140 using anysuitable approach. In some embodiments, covers 120 and 150 may includesnaps 124 and 154 extending from flat surfaces 122 and 152. For example,snaps 124 and 154 may extend orthogonally (e.g., vertically) fromsurfaces 122 and be located at the periphery of surfaces 122 and 154. Bybeing located at the periphery, snaps 124 and 154 may be substantiallyaligned with side walls 112 and 142, respectively, such that the snapsmay engage a portion of the side walls. Snaps 124 and 154 may includeone or more mechanisms for engaging side walls 112 and 142. For example,snaps 124 and 154 may be elastically biased towards side walls 112 and142 such that snaps 124 and 154 may deflect when they are placed overframes 110 and 140, respectively, thus creating an interference orfrictional fit. As another example, snaps 124 and 154 may include a tabor protrusion 126 and 156, respectively, operative to engage acorresponding indentation or tab 116 and 146, respectively, in the sidewall. As still another example, a tape, adhesive or mechanical fastener(e.g., a screw passing through snaps 124 and 154 and engaging side walls112 and 142, respectively) may be used to secure snaps 124 and 154 toframes 110 and 140, respectively.

Each cover 120 and 150 may include any suitable number of snaps 124 and154. For example, a cover may include snaps 124 and 154 offset atdistances larger than the width of a snap. In some embodiments,different snaps 124 and 154 may have different sizes, for example basedon the component 132 lying adjacent the snap on circuit board 130, orbased on the position of snap relative frame 110 or 140 (e.g., a snapadjacent a corner may be wider than a snap in the middle of a wall). Thesnaps may also be distributed along the periphery of the cover using anysuitable approach, including for example evenly, or based on the EMIshielding or structural requirements of the shield.

Frames 110 and 140, and covers 120 and 150 may be manufactured from anysuitable material operative to shield the components of contained withinEMI shield 100 from electromagnetic interference (e.g., from othercomponents of the electronic device). In some embodiments, shield 100may be constructed from an electrically conductive material such as, forexample, metal (e.g., copper, silver, aluminum, steel), graphite,plasma, or any other conductive material. Frames 110 and 140, and covers120 and 150 may include unbroken surfaces, or materials with a mesh orholes (e.g., so long as the holes are smaller than the wavelength of theradiation being kept out).

Because two frames 110 and 140, and two covers 120 and 150 may be usedin the same electronic device, space may be lost between each EMI shield(e.g., along boundary 115). To reduce the space required betweenadjacent EMI shields 108 and 138, shields 108 and 138 may interlockalong boundary 115. FIG. 2 is a top perspective view of an exploded EMIshield assembly in accordance with one embodiment of the invention. EMIshield 208 and 238 may include some or all of the features of EMIshields 108 and 138 (FIG. 1) described above. Frames 210 and 240 may becoupled to circuit board 130 using any suitable approach. Covers 220 and250 may then be placed over frames 210 and 240, respectively, such thatthe electronic device components within the boundary of each frame 210and 240 are fully enclosed.

Using some approaches, EMI shields 208 and 238 may be placed adjacent,and brought together until covers 220 and 250, which form theexternal-most layer of the EMI shields (e.g., because tabs extendingfrom the covers are positioned outside the side walls of the frames),are in near contact (e.g., along boundary 215). To save even more space,however, covers 220 and 250 may be designed to interlock.

FIG. 3 is a perspective view of an assembled EMI shield assembly inaccordance with one embodiment of the invention. EMI shield assembly 300may include first EMI shield 308 and second EMI shield 338 that arecoupled to circuit board 330. EMI shields 308 and 338 may include someor all of the features of any of the EMI shields described above inconnection with FIGS. 1 and 2. First EMI shield 308 may include frame310 to which cover 320 may be coupled, and second EMI shield 338 mayinclude frame 340 to which cover 350 may be coupled. Covers 320 and 350may include snaps 324 and 354, respectively, for engaging frames 310 and340, respectively. To save space between EMI shields 308 and 338 alongboundary 315, snaps 324 and 354 of covers 320 and 350, respectively, maybe arranged such that snaps 324 and 354 may interlock.

FIG. 4 is a perspective view of a detail of the EMI shield assembly ofFIG. 3 along the boundary between the EMI shields in accordance with oneembodiment of the invention. FIG. 5 is a top view of a detail of the EMIshield assembly of FIG. 3 along the boundary between the EMI shields inaccordance with one embodiment of the invention. By the manner in whichsnaps 324 and 354 are constructed, snaps 324, and 354 extend beyond therespective peripheries 321 and 351 of covers 320 and 350, creatingrespective voids 326 and 356 between adjacent snaps 324 and 354,respectively. Voids 326 and 356 may be defined, for example, by the sidewall of the underlying frame, and by the width of adjacent snaps 324 or354.

By sizing and distributing snaps 324 and 354 and voids 326 and 356judiciously, a snap 324 may extend into a void 356, and a correspondingsnap 354 may extend into a void 324 along boundary 315 (e.g., wherecovers 320 and 350 engage). In addition, if snaps 324 and 354 have thesame width (e.g., which would likely be the case if the same material isused for both covers 320 and 350), the depth of each void 326 and 356would match the width of each snap 324 and 356 operative to engage orextend into the void. Thus, the space required between adjacent covers320 and 350 may be reduced from the width of snap 324, plus the width ofsnap 354, plus a clearance factor to only the width of one of snaps 324and 354, plus a clearance factor. This allows the space between adjacentEMI shields 308 and 338 to be reduced up to by half (e.g., by thethickness of the material, for example sheet metal plus any additionaldistance required to clear the snaps). For example, if the width of eachsnap 224 or 254 is in the range of 0.12 to 0.2 mm, the savings may befor example 0.15 mm.

Using this approach, in a top view, it may appear as though the snaps ofboth covers form a single layer placed between the frames of the two EMIshields (e.g., snaps of adjacent shields are substantially or at leastpartially aligned). For example, a single plane may include the innersurface of snap 324 and the outer surface of an adjacent snap 354.

In some embodiments, covers 320 and 350 may have different heights. Forexample, cover 320 may be higher than cover 350 (e.g., when coupled toframe 310). To allow covers 320 and 350 to engage, snaps 324 and 354 maybe offset in the vertical dimension (e.g., along the height of covers320 and 350). For example, snaps 324 may be located above snaps 354 whencovers 320 and 350 engage because cover 320 is located above cover 350.Thus, the void used to place snap 354 near frame 310 may not be adjacentsnap 324 (e.g., at a different point on the periphery of cover 320), butrather underneath a snap 324 (e.g., between the bottom edge of snap 324and circuit board 330).

Any suitable approach may be used to ensure that adjacent covers 320 and350 engage properly. For example, covers 320 and 350 may be shaped suchthat only one possible engagement of covers 320 and 350 is possible. Asshown clearly in FIGS. 3-5, boundary 315 includes angled segment 316.Each of covers 320 and 350 may include corresponding angled portions 321and 351, respectively. The size and shape of angled portions 321 and 351may render any engagement of covers 320 and 350 that does not engageangled portions 321 and 351 impossible (e.g., covers 320 and 350 cannotengage properly, and save space unless angled segment 316 is properlycreated). This may ensure that covers 320 and 350 are properly placed ontheir respective frames, and that EMI shields 308 and 338 are properlymounted.

Other suitable shapes may be used instead of or in addition to angledsegment 316. FIGS. 6A-6D are top views of a detail of an EMI shieldassembly along the boundary between EMI shields in accordance with oneembodiment of the invention. EMI shields 608 and 638 may include covers620 and 650, respectively. Cover 620 may include tabs 624 and voids 626,and cover 650 may include tabs 654 and voids 656. Boundary 615 betweenEMI shields 608 and 638 may have any suitable, non-linear shape thatallows only one reasonable engagement configuration. For example,boundary 615A includes a curved shape, boundary 615B includes severalcurved shapes, boundary 615C includes a single angle, and boundary 615Dincludes a protrusion. Tabs from each cover 620 and 650 may engage alongany suitable surface, including several surfaces if boundary 615includes several surfaces (e.g., boundary 615C includes engaging tabsalong two surfaces of covers 620 and 650). It will be understood,however, that any other suitable shape may be used for boundary 615.

As another example, snaps 324 and 354, and corresponding voids 326 and356 may be distributed along the periphery of each cover 320 and 350such that, along the periphery that forms boundary 315, at least onesnap and void in each cover is sized or located such that only onepossible engagement of the covers is possible. FIG. 7 is a top view of adetail of an EMI shield assembly along the boundary between EMI shieldsin accordance with one embodiment of the invention. EMI shields 708 and738 may include covers 720 and 750, respectively. Cover 720 may includefirst tabs 724, and second tab 725 that is different from first tabs724. Conversely, cover 750 may include first voids 756 that is differentfrom second void 757. When covers 720 and 750 are placed adjacent andengaged, the sizes of tabs 724 and 725, and of voids 756 and 757 may besuch that the only possible engagement of covers 720 and 750 is with tab724 engaging void 756, and tab 725 engaging void 751.

In some embodiments, more than two adjacent EMI shields installed on acircuit board may include tabs operative to engage to save space. Forexample, a two-dimensional array of interlocking EMI shields may beprovided, such that different sides of a particular EMI shield mayengage sides of different EMI shields (e.g., every side of the centerEMI shield of a 3×3 array may engage another EMI shield). This may allowmore components to be individually shielded while limiting the amount ofspace required for each shield.

The above described embodiments of the present invention are presentedfor purposes of illustration and not of limitation, and the presentinvention is limited only by the claims which follow.

1. An electromagnetic interference shield array, comprising: a first frame; and a first cover operative to be placed over the first frame, the first cover comprising at least a first snap operative to engage a portion of the first frame; a second frame separate from and placed adjacent to the first frame; and a second cover operative to be placed over the second frame, the second cover comprising at least a second snap operative to engage a portion of the second frame, the second snap offset from the first snap such that the first and second snaps are aligned to form a single layer between the first and second frames.
 2. The electromagnetic interference shield array of claim 1, wherein the second cover comprises at least two snaps, and wherein the first snap extends between the at least two snaps.
 3. The electromagnetic interference shield array of claim 1, wherein the first and second snaps are substantially in the same plane.
 4. The electromagnetic interference shield array of claim 1, wherein the edge of the first frame adjacent the second frame is not straight.
 5. The electromagnetic interference shield array of claim 4, wherein the edge includes at least one angle.
 6. The electromagnetic interference shield array of claim 1, wherein the first and second frames comprise a wall coupled to a circuit board.
 7. The electromagnetic interference shield array of claim 6, wherein the first and second frames comprise a return.
 8. The electromagnetic interference shield array of claim 1, wherein the first snap comprises an engagement feature for coupling the first cover to the first frame.
 9. The electromagnetic interference shield array of claim 1, wherein space between the adjacent edges of the first and second frames is substantially equal to the width of a single snap.
 10. A cover for use with a frame to form an electromagnetic interference shield, comprising: a substantially flat surface operative to extend up to the periphery of the frame; and at least two adjacent snaps extending vertically from the surface, wherein the snap of a cover of another electromagnetic shield is to be inserted between the at least two adjacent snaps and aligned with the at least two adjacent snaps.
 11. The cover of claim 10, wherein the flat surface does not extend beyond the periphery of the frame.
 12. The cover of claim 10, wherein the at least two adjacent snaps and the other snap are located in substantially the same plane.
 13. The cover of claim 10, wherein frame and the cover are constructed from a conductive material.
 14. The cover of claim 10, wherein the thickness of each snap is the range of 0.12 and 0.2 mm.
 15. An electromagnetic interference shield for use in an electronic device, comprising: a frame coupled to a board of the electronic device; and a cover operative to be placed over the frame, the cover comprising snaps extending vertically from a surface of the cover and operative to engage the frame, the snaps distributed around the periphery of the cover so that the distance between adjacent frames in the electronic device is substantially less than twice the width of one of the snaps.
 16. The electromagnetic interference shield of claim 15, wherein: the frame comprises a plurality of frame engagement features aligned with the snaps; and each snap comprises a snap engagement feature operative to engage the corresponding frame engagement feature aligned with the snap when the cover is placed over the frame.
 17. The electromagnetic interference shield of claim 16, wherein the snaps are operative to disengage the frame to allow access to electronic device components located on the board within the periphery of the frame.
 18. The electromagnetic interference shield of claim 15, wherein the frame is coupled to the board using at least one of soldering, an adhesive, an engagement member, and a mechanical fastener.
 19. The electromagnetic interference shield of claim 15, wherein the portions of the surface of the cover that do not include snaps do not extend beyond the periphery of the frame.
 20. The electromagnetic interference shield of claim 15, wherein the thickness of each snap is the range of 0.12 and 0.2 mm. 